Endometriosis is a condition that often causes pelvic pain, particularly during menstruation but also continuously and over long periods. Pharmacological treatments are only moderately effective or are associated with adverse effects. In this context, the search for non-pharmacological approaches to endometriosis pain is essential. Transcutaneous electrical nerve stimulation (TENS) is a portable pain relief technique that is rapidly developing for the treatment of endometriosis pain. The protocol presented aims to confirm the analgesic efficacy of this treatment for endometriosis pain. It will involve 27 gynecology and pain departments in mainland France. It will offer 30-minute sessions of daily stimulation, either suprapubic or lumbar. Several types of stimulation will be compared, with three 3-month phases, two blind phases, and a 3-month phase in which the system used will be fixed. The aim will be to reduce pain intensity as well as other parameters relating to quality of life and the impact of pain. If the effectiveness of this device is confirmed, it could lead to TENS being made available for endometriosis pain and potentially prescribed by gynecologists and midwives.

The study will be proposed to women of adult age during a routine consultation for endometriosis-related pain, in gynecology and pain centers, in France, if they meet the inclusion and exclusion criteria of the study.

Information will be given to them and a necessary period of reflection not exceeding one week will be granted to them.

First phase: a cross-over trial After giving their informed consent, women will be included and randomized either to the actiTENS mini treatment arm or to the low activity treatment arm for 3 months, followed by a wash out period of 28 days. After this first cross-over period, women initially randomized to the actiTENS mini arm will be switched to the low activity arm for 3 months, inversely patients initially in the low activity treatment arm will be switched to the actiTENS mini treatment for the same duration of 3 months.

During the first cross-over study, women will be treated 60 minutes twice daily by a TENS device applied both on the pelvic anterior and sacral posterior region, with the P2 program.

Second phase: an open-label trial After a wash out period of 28 days, all patients will enter the 3-month open phase where only actiTENS mini treatment will be prescribed for 3 months, women choosing freely the region of stimulation (anterior, posterior or both), the program of stimulation and the duration of stimulation.

Inclusion Criteria:

• Women over 18 years old
• Followed-up in gynecology consultation for endometriosis confirmed by specific imaging (MRI or ultrasound)
• Referred to a gynecological or a pain center
• With chronic pelvic pain (for at least 3 months) related to endometriosis, pelvic pain being the predominant symptom of endometriosis: pelvic pain present at least 15 days per month in the previous 3 months
• Stable and optimal analgesic and hormonal treatments during the last 3 months: any modification of pharmacological treatment in the last 3 months
• Pelvic pain of moderate to severe intensity or greater than or equal to 4 on an NRS of 0-10 on average during the 8 days preceding the inclusion visit and during the inclusion visit.
• Informed about the concept and accepting the use of TENS as a device, a non-drug analgesic treatment.
• Able to understand the use of TENS
• Having a personal smartphone enabling the EndoTENS application to be downloaded
• All women of childbearing potential (WOCBP) must agree to maintain highly effective contraception by practicing abstinence or by using an effective method of birth control from the date of consent through the end of the study: Combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulation (Oral, Intravaginal, Transdermal); Progestogen-only hormonal contraception associated with inhibition of ovulation (Oral, Injectable, Implantable); Intrauterine device (IUD); Intrauterine hormone-releasing system (IUS); Bilateral tubal occlusion; Vasectomized partner, spermicide-coated condoms
• Willingness and ability to attend the scheduled study visits and comply with study procedures
• Affiliated to Social Security.

Exclusion Criteria:

• Symptoms of endometriosis other than pelvic pain, predominant over pelvic pain (pelvic pain is not the main symptom): digestive disorders, unstable bladder, dyspareunia, infertility, fibromyalgia, sciatica, low back pain…
• Present or past allergy to actiTENS mini pads.
• Pelvic surgery planned within the next 11 months.
• Drug or non-pharmacological treatments not stabilized, which could influence the pathology studied during the last 3 months
• Changed of treatments for endometriosis planned in the next 10 months.
• Patient presenting an absolute contraindication to TENS: patient with epilepsy, patient with a defibrillator, a pacemaker, a cochlear implant or other implanted electronic devices, patient with cardiac disorders, patient with decreased or altered sensation or sensitivity in the area to be treated, for example patients with allodynia (pain triggered by a stimulus that is normally painless) in the area to be treated.
• Patient unable to express his consent or patient in deprivation of liberty.
• Patient that already used or know the functioning principles of a TENS device previously to the clinical study
• Contraindications to actiTENS mini
• Pregnancy and breastfeeding
• Patients under guardianship or curatorship and protected adults
• Patients on AME (Aide Médicale de l'Etat = State Medical Assistance)
• Current participation in another research study involving a therapeutic intervention. Participation to an observational research, or a non-interventional research is allowed

The deidentified individual participant data (IPD) that support the results reported in publications may be shared. Additionally, the IPD outlined in the protocol for a planned meta-analysis may also be made available. A data dictionary defining each field will be made available concurrently with the data transmission.

Two years after the last publication

Data sharing requires approval from both the sponsor and the Principal Investigator (PI), contingent upon a scientific project and the PI team's scientific contribution. The founder may also participate in the decision-making process.

Teams seeking to acquire IPD must engage with the sponsor and the IP team to discuss the scientific (and commercial) objectives, the specific IPD required, the preferred data transmission format, and the proposed timeline. The necessity to inform patients about data sharing or the obligation to undertake procedures with data protection authorities will be evaluated.

The provision of data through the secure institutional tools of the sponsor AP-HP will be prioritized.

Technical feasibility and financial support considerations will precede the obligatory formalization of a contract, including detailed description of data processing and general and specific security measures.

The processing must adhere to the European General Data Protection Regulation.